PI Blog – MAVENhttp://lasp.colorado.edu/home/maven
The Mars Atmosphere and Volatile Evolution MissionThu, 23 May 2019 17:08:08 +0000en-UShourly1https://wordpress.org/?v=4.9.10Tracing Mars Atmospheric Loss through Time: the Three Devilshttp://lasp.colorado.edu/home/maven/2016/08/09/tracing-mars-atmospheric-loss-through-time-the-three-devils/
Tue, 09 Aug 2016 16:34:36 +0000http://lasp.colorado.edu/home/maven/?p=5460Rob Lillis is an Associate Research Physicist at the University of California Berkeley Space Sciences Laboratory, a member of the MAVEN Science team and the deputy lead for the Solar Energetic Particle instrument.
Why is the surface of Mars no longer habitable?
Sounds like a straightforward question, right? However, those nine words comprise one of the most vexing questions in planetary science. There is now overwhelming evidence that Mars was once a place where liquid water flowed on the surface and, thus, life as we know it could have thrived, at least episodically. Orbiters have identified branching networks of valleys that most likely were carved by rainwater or snowmelt. Rovers have driven through ancient streambeds and found minerals that can only be formed over many years underwater. However, such stable surface water requires an atmospheric surface pressure much higher than today’s ~7 millibars (<1% of Earth’s pressure) to prevent evaporation and cause greenhouse warming.
Where did this ancient atmosphere go? If it had all been absorbed back into the crust, abundant carbonate minerals should exist on or near the surface. However, extensive surveys of Mars from orbit have revealed very little carbonate, not nearly enough to account for all the carbon dioxide that has been lost. The only other explanation: The atmosphere escaped out to space over billions of years. But how did this happen? What physical processes drove the escape? How did they vary over time as solar radiation and the solar wind buffeted Mars’ atmosphere, which lacked the protection of a global magnetic field? And, most importantly, how much total atmosphere escaped over Mars’ history? ]]>

(Courtesy Rob Lillis)

Rob Lillis is an Associate Research Physicist at the University of California Berkeley Space Sciences Laboratory, a member of the MAVEN Science team and the deputy lead for the Solar Energetic Particle instrument.

Why is the surface of Mars no longer habitable?

Sounds like a straightforward question, right? However, those nine words comprise one of the most vexing questions in planetary science. There is now overwhelming evidence that Mars was once a place where liquid water flowed on the surface and, thus, life as we know it could have thrived, at least episodically. Orbiters have identified branching networks of valleys that most likely were carved by rainwater or snowmelt. Rovers have driven through ancient streambeds and found minerals that can only be formed over many years underwater. However, such stable surface water requires an atmospheric surface pressure much higher than today’s ~7 millibars (<1% of Earth’s pressure) to prevent evaporation and cause greenhouse warming.

Where did this ancient atmosphere go? If it had all been absorbed back into the crust, abundant carbonate minerals should exist on or near the surface. However, extensive surveys of Mars from orbit have revealed very little carbonate, not nearly enough to account for all the carbon dioxide that has been lost. The only other explanation: The atmosphere escaped out to space over billions of years. But how did this happen? What physical processes drove the escape? How did they vary over time as solar radiation and the solar wind buffeted Mars’ atmosphere, which lacked the protection of a global magnetic field? And, most importantly, how much total atmosphere escaped over Mars’ history?

These are the questions that motivate the MAVEN team’s scientific efforts—day in and day out—as we analyze and interpret data from our nine science instruments. Our overarching strategy is to use MAVEN’s observations to understand the processes that cause atmosphere to escape out into space, as they operate under the conditions experienced by present-day Mars. We will then combine that with knowledge of how those conditions have varied over time to estimate the total loss of atmosphere. Sounds simple, right? But as always, and as you probably guessed, the devil is in the details. Or should I say devils?

The first devil is that MAVEN directly measures escaping ions, i.e., particles with a positive electrical charge, but no instrument yet exists to directly detect escaping neutral (uncharged) particles. Therefore we must infer their escape rates indirectly, and we do this in two complementary ways. The first way is by measuring densities and temperatures of neutrals, electrons, and ions, as MAVEN swoops through the upper atmosphere on each orbit, as well as downward-traveling energetic ions (these can “splash out” neutral atoms, like a child jumping into a ball pit, in a process known as sputtering). These quantities let us calculate the rate at which upward-traveling energetic atoms are produced and their rates of escape.

The second way is to observe the faint ultraviolet glow of neutral oxygen and hydrogen high above Mars and use computer simulations of these same reactions and upward passage to estimate the fraction of these particles which are gravitationally bound to Mars versus those which have sufficient energy to escape. Overall, these approaches allow us to characterize the rates of neutral and ion escape from Mars under a variety of seasonal and space weather conditions experienced by Mars in the current epoch.

The second devil is that MAVEN can’t be everywhere at once. As MAVEN’s orbit around Mars gradually changes over time and Mars rotates beneath that orbit, we measure and infer rates of escape at a range of discrete locations under different drivers. In other words, we need a way to “fill in the gaps” in our observations to estimate the global rates of escape and their variability. To do this, we employ sophisticated 3-D simulations of the Martian atmosphere and its interaction with the solar wind. By comparing and matching simulated escape rates to those measured at MAVEN’s location under the same drivers, we can be confident that the global escape rates predicted by these validated simulations reflect reality for present-day Mars.

(Top) ionized oxygen atoms in the upper atmosphere are accelerated away from Mars by electromagnetic forces in the solar wind (colors represent their energy: blue is low, red is high). (Courtesy NASA/GSFC)—(Bottom) Ancient water-carved features on the Martian surface tell a story of a wetter past and hence a thicker atmosphere. (Courtesy ESA/DLR/FU Berlin)

Which brings us to our third devil. These validated global escape rates will be most reliable for the current Mars atmosphere, under the range of solar drivers that MAVEN has characterized. As we turn the clock backward, three issues confound us. First, solar extreme ultraviolet (EUV) radiation and solar wind intensities vary over the 11 year solar activity cycle and unfortunately the most recent cycle was much weaker than normal. Therefore we have not yet characterized their full range that is relevant for the ‘recent’ past (i.e. several million years). Second, these same quantities have decreased gradually over the history of the sun. In the ‘distant’ past (i.e. billions of years) they were at much higher levels that MAVEN will not observe. Third, the atmosphere’s pressure was higher and its composition has changed over time due to this escape. To reliably estimate escape rates under these very different conditions, we will need further 3-D simulations that leverage our hard-won physical understanding of the ion and neutral escape processes occurring in the present-day. The result will be a robust picture of escape rates under the wide range of conditions that likely existed over solar system history.

It should be clear that this approach is ‘bedeviled’ with assumptions and uncertainties. Luckily, MAVEN has one more card to play to determine atmospheric loss: its ability to measure isotopes, i.e. ‘versions’ of the same element with different atomic weights. Escape processes typically favor the lighter isotopes, so by measuring the ratios of light to heavy ones in Mars’ atmosphere today, we can constrain the total amount of that element that has escaped over time.

With this multifaceted approach, the MAVEN science team is continuing to work towards a progressively better understanding of the history of escape rates of the Martian atmosphere—and hence of the atmosphere itself—back to a time almost four billion years ago, when the surface of Mars was suitable for life as we know it.

Based upon the 2016 Planetary Mission Senior Review Panel report, NASA this week directed nine extended missions, including MAVEN, to plan for continued operations through fiscal years 2017 and 2018. Final decisions on mission extensions are contingent on the outcome of the annual budget process.

In addition to ‪‎MAVEN‬, other missions receiving NASA approval for extensions, contingent on available resources, are: New Horizons, Dawn, the Mars Reconnaissance Orbiter (MRO), the Opportunity and Curiosity Mars rovers, the Mars Odyssey orbiter, the Lunar Reconnaissance Orbiter (LRO), and NASA’s support for the European Space Agency’s Mars Express mission.

The MAVEN spacecraft entered the fifth deep-dip campaign of the primary science mission on June 7, 2016. Three maneuvers, like the one shown in this image, brought the periapsis down to 119 km (74 miles) above the Martian surface, where the density of Mars’ atmosphere is about 3.0 kg/km³. (Courtesy NASA’s Goddard Space Flight Center)

‪‎MAVEN‬ began its fifth “deep dip” campaign of the mission this week. Three maneuvers were successfully carried out to lower the periapsis (or lowest) altitude of the spacecraft by approximately 29 kilometers (18 miles), placing MAVEN into the targeted density corridor, where the average density of Mars’ atmosphere is 3.0 kg/km³. The fifth deep dip for MAVEN is uniquely located over the solar terminator (the boundary between dayside and nightside), close to the ecliptic plane, and at a ‪Martian‬ latitude of 35ºN. The three maneuvers—carried out on June 7 & 8—required a total ∆V of 4.6 m/s and resulted in a periapsis altitude of ~119 km (74 mi).

The purpose of the MAVEN deep dip campaigns is to sample a full range of altitudes within the upper atmosphere of Mars, providing complete coverage of this region. At 119 km, MAVEN reaches the Martian homopause, which is the lower, well-mixed region of Mars’ upper atmosphere, where the density is about thirty times greater than at periapsis during a typical science orbit.

Serendipitously, a solar event hit Mars on June 9, just as the MAVEN spacecraft began its latest deep dip campaign. This activity won’t affect the safety of MAVEN or the mechanics of carrying out the deep dip, but should yield some very interesting science results!

Many of the instruments on MAVEN are specifically designed to study solar energetic particles, how they impact Mars’ upper atmosphere and ionosphere, and how they increase atmospheric escape rates.

]]>MAVEN Status Update: September 21, 2015http://lasp.colorado.edu/home/maven/2015/09/21/maven-status-update-september-21-2015/
Mon, 21 Sep 2015 15:23:16 +0000http://lasp.colorado.edu/home/maven/?p=5101-- MAVEN Principal Investigator Bruce Jakosky
As of today, MAVEN has been in orbit around Mars for one Earth year! And it’s been an action-packed year.
Some of the highlights include:

The success of the mission so far is a direct result of the incredibly hard work of everybody who works (and has worked) on ‪‎MAVEN‬. This one year at ‪Mars‬ reflects the tremendous efforts over the preceding dozen years. And the mission continues—we still have two months to go in our primary mission, and then we begin our extended mission. We’re obtaining an incredibly rich data set that is on track to answer the questions we originally posed for MAVEN and that will serve the community for a long time to come.
I hope everybody is as proud of what we’ve accomplished as I am! And here’s to the next year of exciting observations, analyses, and results!]]>— MAVEN Principal Investigator Bruce Jakosky

Courtesy NASA/GSFC

As of today, MAVEN has been in orbit around Mars for one Earth year! And it’s been an action-packed year.

The success of the mission so far is a direct result of the incredibly hard work of everybody who works (and has worked) on ‪‎MAVEN‬. This one year at ‪Mars‬ reflects the tremendous efforts over the preceding dozen years. And the mission continues—we still have two months to go in our primary mission, and then we begin our extended mission. We’re obtaining an incredibly rich data set that is on track to answer the questions we originally posed for MAVEN and that will serve the community for a long time to come.

I hope everybody is as proud of what we’ve accomplished as I am! And here’s to the next year of exciting observations, analyses, and results!

]]>MAVEN Status Update: September 10, 2015http://lasp.colorado.edu/home/maven/2015/09/10/maven-status-update-september-10-2015/
Thu, 10 Sep 2015 15:49:29 +0000http://lasp.colorado.edu/home/maven/?p=5080MAVEN completes fourth deep-dip campaign
NASA's MAVEN spacecraft, in orbit at Mars since Sept. 21, 2014, has completed the fourth deep-dip campaign of its primary science mission. The series of five-day campaigns are designed to lower the periapsis (lowest altitude) of the spacecraft above ‪Mars‬ in order to achieve a targeted atmospheric density corridor and to sample the lower, well-mixed portion of the Martian upper atmosphere. The density at 125 km (78 mi) can be 30 times that encountered during the nominal science orbits, where the periapsis is approximately 150 km (93 mi).
The latest deep-dip campaign began on Sept. 2nd with two "walk-in" maneuvers that lowered the periapsis of the spacecraft to 121 km (75 mi) above the Martian surface. These maneuvers had ∆V (delta-V or a change in velocity) magnitudes of 2.7 m/sec and 0.6 m/sec. The campaign concluded in the early hours of Sept. 10th with the second of two "walk-out" maneuvers, designed to raise the periapsis of MAVEN back to near 150 km. The maximum atmospheric density encountered during the deep-dip was 3.0 kg/km³.
The two "walk-out" maneuvers (executed on Sept. 9 & 10) had ∆V magnitudes of 3.3 m/sec and 0.6 m/sec, and raised the periapsis by 20 km (12 mi) and 4 km (2.5 mi) respectively. These maneuvers returned MAVEN to a nominal periapsis altitude of 145 km (90 mi) and achieved an estimated density of 0.11 kg/km³.]]>

The MAVEN spacecraft entered the fourth deep-dip campaign of the primary science mission on Sept. 2, 2015. Two maneuvers, like the one shown in this animation (click image to run GIF), brought the periapsis down to 121 km (75 miles) above the Martian surface, where the density of Mars’ atmosphere is about 3.0 kg/km³. (Courtesy NASA’s Goddard Space Flight Center)

MAVEN completes fourth deep-dip campaign

NASA’s MAVEN spacecraft, in orbit at Mars since Sept. 21, 2014, has completed the fourth deep-dip campaign of its primary science mission. The series of five-day campaigns are designed to lower the periapsis (lowest altitude) of the spacecraft above ‪Mars‬ in order to achieve a targeted atmospheric density corridor and to sample the lower, well-mixed portion of the Martian upper atmosphere. The density at 125 km (78 mi) can be 30 times that encountered during the nominal science orbits, where the periapsis is approximately 150 km (93 mi).

The latest deep-dip campaign began on Sept. 2nd with two “walk-in” maneuvers that lowered the periapsis of the spacecraft to 121 km (75 mi) above the Martian surface. These maneuvers had ∆V (delta-V or a change in velocity) magnitudes of 2.7 m/sec and 0.6 m/sec. The campaign concluded in the early hours of Sept. 10th with the second of two “walk-out” maneuvers, designed to raise the periapsis of MAVEN back to near 150 km. The maximum atmospheric density encountered during the deep-dip was 3.0 kg/km³.

The two “walk-out” maneuvers (executed on Sept. 9 & 10) had ∆V magnitudes of 3.3 m/sec and 0.6 m/sec, and raised the periapsis by 20 km (12 mi) and 4 km (2.5 mi) respectively. These maneuvers returned MAVEN to a nominal periapsis altitude of 145 km (90 mi) and achieved an estimated density of 0.11 kg/km³.

]]>MAVEN Status Update: February 11, 2015http://lasp.colorado.edu/home/maven/2015/02/11/maven-status-update-february-11-2015/
Wed, 11 Feb 2015 18:50:12 +0000http://lasp.colorado.edu/home/maven/?p=4616Bruce Jakosky, MAVEN principal investigator at CU-Boulder's Laboratory for Atmospheric and Space Physics
MAVEN is about to carry out its first “deep-dip” campaign. This involves lowering the lowest altitude in the orbit from about 150 km above the surface to about 125 km. We do this so that we can measure the properties of that additional 25 km of the upper atmosphere between 150 and 125 km. It doesn’t seem like much, but this lets us go all the way down to the top of what we call the lower atmosphere, and it will let us make the connection then from the top of the upper atmosphere all the way down to the surface.
We’ll use three rocket-motor burns to lower the orbit, spread over three days. We do it gradually so that the spacecraft can “walk in” and we don’t get taken by surprise by anything along the way. Then we’ll stay in the “deep dip” orbit for five days, which covers about 20 orbits around the planet. Finally, we’ll use two maneuvers to “walk” back out and get back to our regular science mapping orbit.]]>Bruce Jakosky, MAVEN principal investigator at CU-Boulder’s Laboratory for Atmospheric and Space Physics

MAVEN is about to carry out its first “deep-dip” campaign. This involves lowering the lowest altitude in the orbit from about 150 km above the surface to about 125 km. We do this so that we can measure the properties of that additional 25 km of the upper atmosphere between 150 and 125 km. It doesn’t seem like much, but this lets us go all the way down to the top of what we call the lower atmosphere, and it will let us make the connection then from the top of the upper atmosphere all the way down to the surface.

We’ll use three rocket-motor burns to lower the orbit, spread over three days. We do it gradually so that the spacecraft can “walk in” and we don’t get taken by surprise by anything along the way. Then we’ll stay in the “deep dip” orbit for five days, which covers about 20 orbits around the planet. Finally, we’ll use two maneuvers to “walk” back out and get back to our regular science mapping orbit.

We carried out the first of the “walk in” maneuvers successfully during the evening of February 10th. It lowered the spacecraft periapsis from ~155 km to ~134 km, and is the largest of the three maneuvers. The second maneuver will be carried out on February 11th. It’s going to be an exciting week!

We don’t stay in this deep dip orbit all the time because the atmospheric density at these altitudes, as tenuous as it is, is too large. The drag on the spacecraft would cause us to spiral into the planet, and the gas could affect our electronics. As a result, we’re planning to carry out these campaigns five times during the one-year mission.

As of today, MAVEN is almost three months into its science mapping mission. We’re still learning how to use the instruments and the data. The mission is going smoothly, and the data are spectacular! We’re planning to try to put it together into a coherent picture of the upper atmosphere in order to present it at the Lunar and Planetary Science Conference in mid-March. That will be the first time that we have real “preliminary science results from the MAVEN mission”!

]]>MAVEN Status Update: December 3, 2014http://lasp.colorado.edu/home/maven/2014/12/03/maven-status-update-december-3-2014/
Wed, 03 Dec 2014 20:46:26 +0000http://lasp.colorado.edu/home/maven/?p=4458David F. Mitchell, MAVEN Project Manager at NASA’s Goddard Space Flight Center
MAVEN is now fully into its Science Phase at Mars and the scientists have been releasing exciting results, not the least of which were recent findings from the Comet Siding Spring encounter. The Imaging Ultraviolet Spectrometer was able to observe intense emissions from magnesium and iron ions in the atmosphere in the aftermath of the comet encounter. The Neutral Gas and Ion Mass Spectrometer directly sampled and determined the composition of comet dust in Mars’ atmosphere, something that has never been done before. Our Solar Energetic Particle instrument observed significant solar activity both in the form of flares and coronal mass ejections from the Sun to Mars. We also generated a map of Mars’ ozone layer in the lower atmosphere. Finally, we’ve been able to provide a view of the escaping atmosphere of Mars showing the loss of atomic oxygen, atomic carbon, and atomic hydrogen.
Great science with much more to come!]]>David F. Mitchell, MAVEN Project Manager at NASA’s Goddard Space Flight Center

The first demonstration of MAVEN’s capability to relay data from a Mars surface mission, on Nov. 6, 2014, included this and other images from NASA’s Curiosity Mars rover. The image was taken Oct. 23, 2014, by Curiosity’s Navigation Camera, showing part of “Pahrump Hills” outcrop. (Courtesy NASA/JPL-Caltech)

MAVEN is now fully into its Science Phase at Mars and the scientists have been releasing exciting results, not the least of which were recent findings from the Comet Siding Spring encounter. The Imaging Ultraviolet Spectrometer was able to observe intense emissions from magnesium and iron ions in the atmosphere in the aftermath of the comet encounter. The Neutral Gas and Ion Mass Spectrometer directly sampled and determined the composition of comet dust in Mars’ atmosphere, something that has never been done before. Our Solar Energetic Particle instrument observed significant solar activity both in the form of flares and coronal mass ejections from the Sun to Mars. We also generated a map of Mars’ ozone layer in the lower atmosphere. Finally, we’ve been able to provide a view of the escaping atmosphere of Mars showing the loss of atomic oxygen, atomic carbon, and atomic hydrogen. Great science with much more to come!

Final pre-Science Phase checkouts of the MAVEN system also included a full demonstration of the Electra Relay capability between MAVEN and the Curiosity rover on the surface of Mars. MAVEN relayed the image shown here from Curiosity’s Navigation Camera to Earth on November 6th. This image shows part of the “Pahrump Hills” outcrop and was taken at Mars on October 23rd.

On a personal note, I transitioned off of the MAVEN Project in November and am moving on to my next adventure. Per plan, the standalone MAVEN Project will be managed within Goddard’s Space Science Mission Operations (SSMO) Project. Led by Rich Burns, SSMO is a multi-mission operations project that receives missions from the “development projects” and manages them through long-term operations. The MAVEN Principal Investigator, the science team, and all MAVEN partner institutions (University of Colorado/Boulder, NASA/Goddard, University of California/Berkeley, Lockheed Martin, NASA/Jet Propulsion Laboratory) will continue on with the MAVEN mission.

This will be my last MAVEN monthly update, but I may send out a note on occasion when a press release comes out. You can continue to follow MAVEN on Facebook and Twitter (MAVEN2Mars).

It has been a great pleasure and honor to work with this team, really a highlight of my career. I’ll leave you with a video titled “Voices of MAVEN” that was recently posted to the web. The people in the video represent hundreds of others who have made MAVEN such a great mission.

The instruments onboard the MAVEN spacecraft are labeled in this artist’s representation of the Mars orbiter. (Courtesy NASA/GSFC)

As of Friday, November 28, the MAVEN science instruments have been turned back on following safe-mode recovery, and we have resumed collecting science data.
]]>MAVEN Status Update: Nov. 22, 2014http://lasp.colorado.edu/home/maven/2014/11/22/maven-status-update-nov-22-2014/
Sat, 22 Nov 2014 15:28:46 +0000http://lasp.colorado.edu/home/maven/?p=4445

An artist’s rendition shows the MAVEN spacecraft in orbit around Mars. (Courtesy NASA/GSFC)

After ground testing and careful review over the last two days, MAVEN was successfully brought out of Safehold Mode this afternoon. The spacecraft is operating nominally in Earth-Point Mode with high-rate communications. All the instruments are safe and are currently off. The spacecraft will be monitored over the weekend to ensure a safe condition before the instruments are turned back on.

An artist’s rendition shows the MAVEN spacecraft in orbit around Mars. (Courtesy NASA/GSFC)

MAVEN went into safehold mode on Wednesday, Nov. 19. The spacecraft goes into this state autonomously, when it detects a problem with its operations, to ensure that it stays safe and in contact with Earth. Safehold was triggered by a timing conflict between commands. This is part of learning how to operate the spacecraft in a new environment, as this is the first time the spacecraft has been in its full science-operations scenario. The instruments have all been turned off and are safe, the spacecraft is healthy and in high-data-rate contact with Earth. The spacecraft operations team is currently developing the schedule to return MAVEN to science operations.
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